Telephone system



NOV. 4, 1930. T CRQCKER 1,780,617

TELEPHONE SYSTEM Filed Jan. 28. 1929 2 Sheets-Sheet l HOLDEVISS O L FL E@ *l//7 :Fini d20 Thames FCM/:kar

Nov. 4, 1930. T. F. cRo'cKr-:R 1,780,617

TELEPHONE SYSTEM l Filed Jan. 28, 1929 2 Sheets-Sheet 2 M En.

Patented Nov. 4, 1930 UNITED l'STATE-S tLI-IolvIAsl F.0RCKER, orv CHICAGO, ILLINoIsAssIGNoR y'ro RESERVE IIoLnINelcomn PANY, yoRIzANsAs CITY, MIsso-URLA CORPORATION CRDELAWARE.

TELEPHONE SYSTEM i Apimcauon fue@ January 2s, 1929.` serial No. 335,443.

This invention relates to telephone sys'- tems in general but is more particularly concerned. with small private installations of the e type commonly used commercialestablishments and in various branches of municipal administration suchas ire and police departments. The invention is concerned primarily with apparatus for rendering special services Y in systems of the above type.

tomatic.exchanges7 abbreviated as PQA. X.,

and may vary in size' from a vfew lines to several hundred lines. In referring to the automatic exchange, the abbreviation P A. X. will be used throughout the specification.

In addition to the automatic exchange, a telephone system of the above type usually includes'a special service desk or operators position. This desk may be in charge of an operator or a desk sergeant and is usually located in the department headquarters.A The main purpose `of this special service desk is to provide a central point towhich the various patrol oiiicers may` report and from which they may ,obtainA information Apertinent to they dischargeof theirduties. Special means may also be provided ,softhat a selected group of lin essuch as those extending to the various branch policestationsfmay be called as a group for. conference purposes or so that an important ymessage can be transmitted simultaneously to all stations concerned.

The object of the invention is the provision of new and improved circuits forsystems Yof the fabove type with particular referenceto the operatorstelephone circuit and associated ltrunk circuits. ',It isto be understood, however, thatthe application of the invention is not limited'to a police depart Q ment P. A. 'X. .andv that the invention is described in conjunction ltherewith merely for the purpose ofy illustrating one methodfof utilizing the features-of theinvention. Other applications will be readily apparent. y

According to one feature of the invention., a two-way trunk extending between the P.

A. `X. and the operators position terminates in af relay group at the special servicedesk-` A- battery feed bridge inthe relaylgroup normally supplies battery `tothe operators telel phone set. On'outgoing calls overthe trunk,

the battery feed vbridge is disconnectedV and.

a loopcontrol circuit from the operators set is extended to the regular. switch train in` the P. A. X.

Accordingto another feature of the invention, a single key is used to extendy outgoing'calls and to answer incoming calls over the two-way trunk. As long as the keyisin answering position a busy potential is maintained on the guarding conductor to prevent another call from coming inwhile theoperators set isv connected up. The release of the switch train in the P. A. is not in-` terferred with.

Another vfeature is the arrangement Where' by importantmessages may be quicklyltrans lili aty

mitted to a'selected group of stations. These svt-ations can be connected to the group calling;

apparatus regardless of'their busy or idle condition.` `Eachstation of the group is provided with a separate battery feeding bridge when connected to the common talking circuit which improves transmission and affects the operation in other ways which will be explained in detail later on. l.

Another feature is vthe arrangement where# Y by an incoming callmay be telephonically connected to thegroup call circuit to permit the party making the call to transmit-an im-V portant message to the groupl stations or-to listenin while the: message is being trans- .i

mitted by the operator. Other calls'f'in'p'rogress vvcan be disconnected from v the operators setto prevent `other than the group sta-- tions from hearing the message. i

,The foregoing features, togetherwith others lnot specifically mentioned,v will be described fully hereinafter.y g g Theaccompanying drawings comprising Figs. l and 2 show by means of the usual cir cuit diagrams a suflicient .amount of equipment in a telephone `system embodying the features fof .the invention to enable the invention to be understood. kThe drawings should be arranged with Fig'. 2 directly beneathFig.

1, so that the four vertical lines extending` to the lower and upper margins, respectively, of the two figures will be in alignment.

Referring now to Fig. 1, the operators telephone set T is of the well-known cradle type with an 'anti-side tone circuit, comprising the usualV talking and impulsing instrumentalities. A telephone set of this type is shown in United States Patent No. 1,689,598 to H. C. Pye. Y The bells shown in the drawing are ordinarily provided with telephone sets but have no function in the present instance other than to balance the transmitter and receiver circuits. l

A two-way trunk comp ising three conductors extends from the trunk relay group TRG to a line switch LS in the P. A. X. The trunk is also accessible in the banks of the connectors of the P. A. X. The key K1, located-at the operators position, is used for extending or answering calls over the trunk, rlhe trunk relay group is interconnected with the group call equipment in such a manner that the initiation of a group call will release an outgoing call, as will be described in detail later on.

VReferring to Fig.w 2, the common group relay equipment CGR is connected to the oper# ators telephone set by means of the key K2'. Associated with the common relay group are a number of individual relay groups of which one relay group, IGR, is shown. The other individual relay groups are similar in every respect to IGR and are connected in multiple to the common equipment as shown. Each telephone line from a group station such as 'I terminates in a relay group such as IGR from which connections extend to a line switch LS1 in the P. A. X. Calls over these lines normally proceed as ordinary calls over the regular P. A. X. switch train. It will be noted that a signal lamp L;2 is provided for each individual relay group.

Relay group IR terminates a selector level trunk. Calls coming in over this trunk operate the signal lamp L3 and the calling party is given a ring back tone. A battery rfeeding bridge connected to the trunk supplies transmission battery to the calling party. In case it is desired to hold a' connection temporarily while makingother calls, the key K3 is operated to the left. If the calling party releases before the key is restored to normal position, a busying potential is placed on the guard conductor to prevent another call from coming in over the trunk.

I-Iaving briefly described the various pieces -of apparatus and the general functions thereof, a detailed description will now be given.

YWhen the operators telephone set is not in use the transmitter-receiver member will be resting` in the cradley normally provided and plunger .Bwill be depressed, opening the contacts 6 and 7.l The talking conductors will, therefore, be open atthe above contacts and no battery will flow in the circuit of the transmitter and receiver. IVhen the transmittenreceiver member is lifted from the cradle, the plunger 5 is actuated by a spring (not shown) permitting the contacts 6 and to .close the talking conduct-ors through to the transmitter and receiver.

In order to make a call over the outgoing trunk, key K1 is operated to the right. A circuit is closed from battery, contact 134;, conductor 132, winding 4of relayj103, armature 11iL and its resting contact, and resting 'contact and armature 116 to ground. Relay 103 operates over the above-traced circuit and at armature 117vand its working contact connects the speaking conductor 2 through to the line'switch LS by way of armature 124 and its resting contact and conductor 128. At armature 119 and its working contact talking conductor 3 is connected through to line switch LS by way of normally closed contacts controlled by armature 127 and conductor 129. rlhe line switch is operated in the usual way over a loop including an operators transmitter, receiver, calling device, and a contact controlled by plunger 5. The line switch operates in the. well-known manner and by way of wipers 136, 137, and 188 eX- tends the connection to an idle trunk such as that comprising conductors 138, 189, vand 1110. This trunk leadsto a local selector in the I). A. X. The operator may now proceed to set up the connection by operating the calling device CD. Vhen the calling device is turned off-normal the transmitter and receiver are shunted out in the usual way to improve the impulsing circuit. As the calling device returns to normal the interrupter springs are opened in the'usual vway and interrupt the loop to operate the selector and other switches in the I). A. X.

The operator may release the connection by restoring the connection key K1 to normal, thus opening the circuitof relay 103 which deenergizes and opens the loop circuit to the line switch at armatures 117 and 119. The battery feeding bridge 104 is again connected across the talking conductors 2 and 8 at normally-closed contacts controlled by armatures 117 and 119. In the foregoing connection it is assumed that the group call equipment is not in use and relay 101 was not energized. The operation of-this relay will be described in detail at a point further along in the speciiication.

Assume now that a call is extended tothe trunk by vway, of a connector in the P. A. X. The o-peration of connector'and line switch underthese circumstances is well known in the art and will not be described in detail. If the trunk is idle the test wiper of the connector finds battery potential on the test contact and switches through in the usual manner. The cut-off relay of the line switch also operates and disconnects the normal bat- `tacts,.lconduc`tor'128, armature 121 and its resting contact, condenser. 'l1-2, winding 'ot relaylO, conductor '129,- bank contact and wiper of the eonnector'to ground. Relay 107 Operates lin response to the ringing current 'i1n-' pulses from the' connector and at armature 128 and its Working contact closes an obvious eir-- cuit-for relay 106,.. Relay 100` operates and at' larmatiuef120 and its working Contact closes a locking circuit for itself including armature 122and its resting contact. At-arma-v ture 124 arpoint in the talking circuitis opened to ypreventany kpossibility of ringing current being connected tothe operators set when the call is answered.'` At armatures'125 and 127 apart of the ring-cuteoificircuit is closed. vRelayxlO'? continues to operate each time an impulse ofiringing currentis transmitted bythe connector but has no further functionin this connection. rlhe initial op-` eration of relay 107 and-the subsequent locking offre/lay 106 places a groundA onconf du'ctor 131 which `lights thesignal lamp L1,

thus notifying Jthe operator that lacall has come inover the trunk. I

ITo answerthe call'key K1. is operated-to the.

the .left, thereby..,clo'sing a circuit from ground, kcontact 135, conductor 133, winding of relay 10"2',winding` of relay V105, t'o battery., Relays 102 ,and y105y operatel vover the abovetracedcircuit. Relay-102, on operating1 at armature 116 and its working Contact :con-

nects ground to release trunk conductor 130, the purpose of which will befdescribed laterl on.' Relay '105, on'l operating', at a'r'ifhaturer 120 and its :working'contact closesr a pointi-nv the `talking circuit, armature 121,'the'cir-` cuit of relay 107 is opened at the resting'con-4 tact, and the ring=trip circuit is closed attlie working contact. vThe' ring-cutio-if' lrelay "of the connectorfoperates l overI the `prei'fiouslyv traced ringing circuit except that armature 121 being Voperated resistance 110, armature? 125, armaturez122, and lground arenowv con neeted up and the' relay operates over this direct current circuit.

relay ,deenergizesk Theremovaliof ground romthe locking circuito; relay-100also en? Y l winding of relay 207 and other correspondtinguishesy the lamp I L1. At Y armature [123 and its working contact the talkingucireuit f visclose ;l"through'to conductor 3;y Shortly afterrelay 105 operates relay 106, which is slow-acting, deenergizes and. at contacts con# trolled b'y'armature 12'? eonipletestlie talking` circuit which may betracediby way ofcon ductor v128` and thence throuvli' there ular Y y n g At armature .I '122 ,the s locking circuit of relay 100 is opened, -and the talking circuit of the connector. The battery feeding impedance 1041'is now bridged across the' talking'conductors at contacts controlled by armatures 117 `aod 119, feeding 'talking battery tothe operators telepone set. 1n .case the calling subscriber hangs up, the switches in tlielautomatic exchange will re-y leasein the regular way. lf they operator does 'not restore the keyK1 immediately the groundfon the release trunk conductor'by way of armature 110 and vits working Contact will prevent another call from coming ineeny the trunk at vthis time.V Vhen the k,operator finally restores key K1 to normal the' circuit for relays 102 and105 is opened and these relays `return to normal. connection 'itis assumed that the group call ing circuit' was not in use and that relay 101- group of'stations such as station T.- Key K?" is opeiated,clos'ing the following circuit: ground 4by -waylof resting Contact and arma#V turej115, resistance 113, conductor '1412, contact 214, armature 215 and its resting Contact, windingof slow-acting relay 202 to battery; Relay 202 operates and at armature 217' and its working contact closes an obvious circuit for relay 203. 'Relay 203 operates and at armature 218 closes a circuitfor the upper winding of f relay 201. and at armature 215l and its working Contact closes a locl'iingci'rcuit forits lower winding including operated contacts 213, conductor 141, winding of relay 101 to ground. Relay 101 operates and disconnects ground from the starting leadv142, and at armature 114 opens the calling circuit oi the outgoing trunk relay group-TRS.. *Relay 201 aisoopens the circuitof relay 202,

characteristics.' l Relay 203*7 inthe meantime, has at armature y219 and its working Contact closed-fa circuit from ground to normally closed contacts controlled 'by armature 229,

'cuit for itself'includin'g armature 229 and'its working'contact, armature 223 and its resting Contact, and `operated contacts 210 to ground. At armatures'227and 231,and theirrespective working contacts, the conductors 238 and 239 As in the previous Relay 201 operates which, however, doesv not release immediately dueto its slow 'release otv the line extending tc the station T are connected to the ringing circuit which may be traced from battery, by way ot ringing current generator G, winding ot relay 206, armature 222 and its resting contact, armature 227 and its working Contact, conductor 238, telephone instrument at station T, conductor 239,

armature 231- and its working contact, arma` Ature 225 and its resting contact to ground.V The other lines in the group corresponding to that extending to station T are also connected up to the ringing circuits of the various individual relay groups, such as IGR, which are connected in multiple to the common relay group CGR as shown. Assuming` that station T' was not busy in another connection at this time, the bells at that station will be rung continuously over the" ringing circuit previously traced. l/Vhen the receiver is lifted at the called station a direct current path is closed over which relay 206 operates. In case station T had been busy in another connection when the group call was made, the operations previously described would be the same except that the receiver being o at the called station, relay 206 would operate immediately over the called station loop. On operating, relay 206 closes a circuit ior relay 205 at armature 220 and its working contact. Relay 205 operates and at armature 224e and its working contact closes a locking circuit for itself including armature 230 and its working contact. The talking conductors of 'the Ycalled line are disconnected from the ringing circuit at armatures 222 and 225 and their resting contacts and at their respective working contacts are connected up tothe two windings of battery feed relay .2011.` At armature 223 and its resting contact the locking circuit of relay 207 is opened; relay 207, however, is slow acting and does not release immediately. Relay 204 operates over the previously traced called line loop and at armature 220 and its working contact closes another locking circuit for relay 207. At armature 221 and its resting contact the circuit ot lamp L2 is opened and the lamp is consequently extinguished. Similar operations take place in leach of the other relay groups as the various called stations answer. lVhen all lamps, such as L2, have been extinguished the operator is informed that all sta-` tions have answered and may proceed to transmit the message. n

Talking battery for the operators set is fed through the impedance 104 of trunk relay group TRG. It will be noted that relay 101 operated in series with relay 201 when the group call was extended. Relay 101 at armature 114 opens a circuit of relay 103 which is without eiect if. no call is in progress on the outgoing trunk. However, if an outgoing call has been in progress over this trunk, the release of the relay 103 opens the circuit to the equipment in the automatic exchange and also connects battery feed relay 104 to the operators telephone set. Incoming calls over the two-way trunk would not be ailected and consequentlyV a calling station would be connected up with the group call equipment, thus permitting a party on this line to transmit a message to the station of the selected group. Incoming calls, however, may be disconnected from the group equipment by restoring key K1 to normal. It is apparent that as long as the group call equipment is in use the operator is prevented from making an outgoing call over the two-way trunk but is not prevented from answering calls over this trunk.

Returning now to the group calling equipment, it will be noted that relay 207 on operating, at armature 228 and its working contact connected a ground to release trunk conductor 234 which serves to mark the line busy to connectors in the automatic exchange. In case a call had been in progress from the sta-v tion T when the group call is made, this ground would serve to maintain the automatic switches in operated position during such time as station T is connected to the group call equipment.

Assuming now that the party at station T wishes to be disconnected from the group equipment without waiting for the operator to release the group connection. rBy actuating the switch hook the circuit of relay 204 is opened and that relay releases, thereby opening the locking circuit of relay 207 at armature 220. Relay l207 deenergizes and connects the talking conductors of the station T back to the trunk conductors leading to line switch LS1. At armature 228 ground is removed from release trunk conductor 234, thereby releasing the switches in the P. A. X. and also removing the busy potential from the test contacts of the connector banks. The lockingcircuit of relay 205 is opened at armature 230 and that relay restores, thereby connecting up the normal ringing circuit, which, however, is now opened at armatures 227 and 231 and their respective working contacts. Other stations of the connector group are not affected in any way and the lamp L2 does not light again.

When key K2 is restored to normal, the

Vinitial locking circuit for relays such as 207 is opened at contact 210 and the operators telephone set is disconnected from the group circuit at contacts 211 and 212. The locking circuit for relays 201 and 101 is opened at contact 213 and these relays restore. Relay 101 again connects ground to the starting conductor of the group call equipment at armature 115 and its working contact, and also closes a point in the. circuit of relay 103, again making the trunk available for outgoing calls. Relay 201, on restoring, opens a point in its locking circuit at armature 215 and at'armature 216 and its working contact closes the normal energizing circuit for relay 202. The individual relay 'group equipv ment, however, is still under the 'controlfof the called station and when the various sta? tions disconnect, 'this equipment releases kas previously described. n c t Information calls areextended to the operator Vby Way of 'selector level trunks ter-` to maintain the lswitches'in the automatic p back tone.`

exchange in operated'position; at armature 263 andits working Contact an obviousciiL cuit is closed forfrelay 254;'at'ar'mature 264k and its working contact va circuit is closed for lampL3 including armature 259 and its resting contact and conductor 274C. `Lamp LS lights, to indicate to theoperator that a call has come in over thelinformation trunk. The calling'party is informed thatthe Acall has' been extendedbygmeans of the ringa To answer the call key Kisoperated to the right, thereby connecting the operators telephone set to the talkin relay group IR at contacts 2%1 and 272 At contactl273 a circuit is closed for the lower winding of relay 251 which operates and at armature 259 and its working Contact closes a locking circuit for its upper winding in- Y Y cluding armature 264 and its working contact. At armature 2,58 the ring-backtone is disconnected from the line and at armature 257 a groundl is placed on abranch'of the release trunk conductor 268 which, however, isopen at armature `265 and its resting c ing the lamp. `The call may now proceed,. v v

`*tensionjof aconne'ctionfcver said lirsty trunk contact. The operationV .of relay 251 also opens the circuit of'lamp L3 at armature 259 and its resting contact,fthereby extinguishtalking battery for the calling line being fed f through relay 252 and talking battery for the operators telephone circuit being fed through impedance 104 of relay group vTRG.

Shouldl the operator desire tohold up the connection while making another call, key Ks is operated to the left, thereby discon-l necting the operators set from thetalking leads of the trunk and closing another locking circuit for relay-251 including Contact 270. The circuit for hold lamp L4 is closed Y at contact 269, this lamp lighting toindicate to the operator'thatthe call is being held.

ov Conductors @fred thisrelay de energizes.

- "When the 'receiver is replaced at the calling station the circuit of relay 252 isopened and-that relayrestores followed by theres- `tor'ationlof relays 2531 and 254, both of which retain their armatures in operatedposition a short time kafter relay 252 restores, due to their'slow releasing characteristics; Relay 253 on restoringremoves ground from release trunk conductor 268, thus permitting'v the switches inithe P. Xto release the regular manner. Relay 254.- remains` oper'- atedv ak short time after relayl 253 restores and'niaintains the release trunk `l conductor opened at armature 265.y When these'relays are restored to normal,ground 'fronifarma ture 257and` itsworking contactis placed on release'trunk conductor 268 by way of arma'- ture 265 and its resting contact to markthe trunk busy to incoming calls. This ground is maintained on the' guarding conductor when key K3 isfoperated in order to prey vent akcall from Coming` in when theequipment is not in condition to give theV propery signal 4to the operatorl or the ring-back sig- Vnal to the calling station. d i u t will be noted that vas *long as key vK3Y is operated to the right the incoming'call is connected to the operators set and may hear conversation lon either the group call equipment loren the two-way trunk.y Toldisconneet ther information trunk from the talking circuit it is only necessary to restore key vK3 to normal or toholding positionl When l@ is restored to normal position the; energizing circuit lof relay 251 is opened andl if the calling-party ,has previously 'disconnect- If the calling.

party 'is-still on theline, relay 25lf'remains y operated overits'upper winding." Signal f ,lai'npL'd .does not light atvthis time since its y in the "appended claims.-r What is claimedis: 'i

"l l.'k In fla telephone system, an i. operatorsv telephone, a firsttrunk'and ya secondtrunk,

means for extending a connection from said telephone over yeither of said `tr unk'sf,abat-` teryv feeding bridge"normally Iconnected to said 1t-elephon'emmeans responsive tothe eX-Y for disconnect'ingsaidbridge, and means responsive to the extension of a connection over nection fandfo'r reg-connecting said bridge. l l' InYatelephonesystem,an'operators po- ,Y l Y sition,an' automaticv exchange, a trunk eX*` tendingfrom the operators position lto the exchange, said trunk comprising two normal-Y i lyj disconnected sections, means for extending aconnectionfrornthe operators positionto l the exchange or from the exchangeto the op- 'er'atorsposition via said trunk, a relay bridged across the lirst section of said tru-nk, a second relay bridged across the second sect-ion of said trunk, meansresponsive tothe extension of a connection from the operators position for disconnectingV both of said relays lfrom the trunk and for directly connecting kthe two sections of said trunk, and means responsive to the extension of a connection from the exchange for disconnecting only said second relay and for connecting the two sections of said trunk through condensers.

3. In a telephone system, an operators position, a lplurality of stations, a plurality of signals at said position each of said signals corresponding to a particular one of said sta tions, a common talking circuit, means for eX- tending a connection from said position to said talking circuit, means responsive to said connection for simultaneously signaling said stations, and Ymeans responsive vlien a staytion answers for connecting the station to saidcommon talking circuit and for actuating `the' corresponding signal.

4. In a telephonefsystem, an operatorsposition,'a plurality of. stations, a common talking circuit, means for extending a talking connection from said position to said talking circuit, means responsive to the extension of the connection for simultaneously signaling said stations, `means responsive when a station answers for connect-ing the station to the common talking circuit, and battery feeding bridges individually connected'to each station duringthe connection.

Y 5. In a group calling circuit, a common talking circuit` a plurality of lines, means for simultaneously signaling said lines, means for connecting said lines to said talking circuit, and means for connecting battery to each line through a separate feeding bridge responsive to the connection of the line to the common talking circuit.

6. In a telephone system, an operators position, an incoming trunk, a plurality of stations having individual lines any ofwhich may be idle or busy in vother connections, a group calling, circuit, means controlled by the operator for. establishing a vconnection with said stations l simultaneously via said group calling circuit regardless of the busy or idle con-dition of saidstations, kandmeans controlled by the operatorl for establishinga Y talking connection between said'incoming trunk and said group connection. A

v'i'. In; a telephone system, an operators telephone set, a 1two-way trunk line, means for connecting ysaid set .to the trunk line to extend an outgoing. call or to answer an incoming call, a source of'current normally connected across thel talking conductors of vthe Vsetfor supplying talking currentv or incomingl calls, Qand means for disconnecting said current source on outgoing calls.

8. In a telephone system, an operators telephone lsetwa .plurality off-.trunk lines adapted to be associated with said set, a source of talking current normally connected with said set, and means for. disconnecting` said current'source from the set responsive toa across the talking conductors of tlie iirst section, means responsive to the answering of an incoming call over the trunk .line for connecting the talking` conductors of the two sections through condensers, and means responsive to the extension of an outgoing callover the trunk line for directly connecting the talking conductors of the two sections and for disconnecting said current source.

l0. In a telephone system, an operators position, a plurality of stations, a line for each station, a common talking circuit, means for extending a talking connection from said position to said talking circuit, means responsive to the extension lof the connection for simultaneously signalling said stations via the associated lines, means responsive when a station answers for connecting the associated line to the common talking circuit, and battery feeding` bridges individually connected to each line during the connection.

In Witness whereof, I hereunto `subscribe my name this 25th day of January, A. D.

THOMAS F. CROCKER. 

